Pectoral Morphology in Doliodus: Bridging the ‘Acanthodian’-Chondrichthyan Divide

Doliodus problematicus (NBMG 10127), from the Lower Devonian of New Brunswick, Canada (approx. 397–400 Mya) is the earliest sharklike jawed vertebrate (gnathostome) in which the pectoral girdle and fins are well preserved. Its pectoral endoskeleton included sharklike expanded paired coracoids, but Doliodus also possessed an “acanthodian-like” array of dermal spines, described here for the first time. Doliodus provides the strongest anatomical evidence to date that chondrichthyans arose from “acanthodian” fishes by exhibiting an anatomical mosaic of “acanthodian” and sharklike features.